The present invention relates to brakes and more particularly to a double brake protection device for elevator with improved characteristics.
Conventionally, a counterweight is provided in an elevator for balance during running. However, such balance may be compromized when persons enter the car of elevator. This unbalanced condition (i.e., the weight of car is significantly heavier than that of counterweight) may be worsen after brake is released. As a result, car may fall suddenly due to law of gravitation. This may endanger the lives of persons in the car. Thus improvement exists.
It is therefore an object of the present invention to provide a brake protection device for an elevator comprising a main motor assembly including a first motor, a first shaft rotatably coupled to the first motor, a first sheave driven by the first shaft, a reduction gear coupled to the first shaft; a brake coupled to the main motor assembly, the brake including a rod-like spring-biased hand brake on the top; emergency means including a pair of idler wheels, a second sheave, a cable interconnecting the elevator and the second sheave through the idler wheels, a pair of pivotal link mechanisms coupled to the idler wheels, and a clutch having a recess coupled to one end of each link mechanism wherein the clutch is disengaged in a disabled state of the emergency means; and a secondary motor assembly coupled to the clutch, the secondary motor assembly including a second motor, a second shaft rotatably coupled to the second motor, and a third sheave coaxial with the second shaft, the third sheave having alternate peaks and valleys on a periphery in contact with the hand brake; wherein the cable is pulled to rotate the second sheave and the idler wheels; the link mechanisms are pivoted through a linking of the idler wheels for engaging the clutch; in response the third sheave rotates to cause the valleys and the peaks of the third sheave to engage with the hand brake alternately wherein when the hand brake is engaged with the peak of the third sheave, the hand break will be pulled down a predetermined distance for releasing the brake, or when the hand brake is engaged with the valley of the third sheave, the hand break will be pulled up the predetermined distance for applying the brake; and in response the elevator slows down stepwise until fully stops.
In one aspect of the present invention, the second motor is operated by battery means.
In another aspect of the present invention, the device further comprises an electromagnetic mechanism above the hand brake, the electromagnetic mechanism having a spring-biased lever extended therefrom, the lever being biased to its highest position in an unexcited state of the electromagnetic mechanism and an extension coupled to a bottom of the lever.
In a further aspect of the present invention, the electromagnetic mechanism is operated by either a backup power of a building or battery means.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.